In the search for solar heating means with high operating temperatures, it has been known for some time, that a honeycomb structure of a material which acts as a black body to heat radiation will be a good thermal barrier against heat travelling along the honeycomb cavities, provided that the heat path is long compared to the transverse dimensions of the cavities. This assumes no net fluid flow is present in the direction of heat flow along the cavities. Geometry will almost eliminate and certainly mitigate the effects of convection currents. Honeycombs of metal foil have been constructed, which admit most of the light incident within 40 degrees of the honeycomb axes, while acting as a reasonable heat barrier, because of a coating of material transparent to sunlight but almost black to heat radiation. It has been proposed by some to use aluminized Mylar as the material of the honeycomb. Labor to produce the structure is relatively high. Another problem with an aluminized Mylar honeycomb is that a significant amount of sunlight is absorbed by the structure, especially at large angles. Also it is open to the atmosphere, and rain can enter the structure. Wind can also blow cold air and dust in and out. Thus, glass plates must enclose the honeycomb in most areas. The cost of the glass structure is additional. Furthermore, the glass will reflect some incident light causing a further loss of power. The most desirable configuration would be a glass honeycomb attached to a glass plate, but this up to now has been difficult and expensive to produce by present techniques of producing the honeycomb and plate separately for later joining.